Color calibration machine



June 22, 1937. "F; A. ROGERS 2,084,598

COLOR CALIBRATION MACHINE Filed April 8, 1935 m/z/s/v 7-27 F. A. QOGEQSTITURNE Patented June 22, 1937 UNITED STATES 7 2,084,598 COLORCALIBRATION MACHINE Fred A. Rogers, Portland, reg.,

assignor to Rainbow Laboratories, Portland, Oreg.

Application April 8', 1935, Serial No. 15,158

1 Claim.

This invention relates generally to the calibration of colors, that is,to the setting up of astandard of values by which colors can bedesignated and distinguished from each other, and

6 particularly to a-color calibrating machine by means of which this isaccomplished.

The main object of this invention is the provision of an exceedinglysimple and eflicient form of color calibrating machine whereby colorvalues maybe accurately determined, compared, and

- current is flowing through the cells in orderthat the utmost precisionmay be obtained, and

cannot ailfect the accuracy of the reading being taken.

The fourth object is the provision of special form of balancingmechanism whereby a definite or zero balance may be obtained before acomparative reading is taken.

I accomplish these and other objects in the manner set forth in thefollowing specification as illustrated in the accompanying drawing, inwhich:

Fig. 1 is a longitudinal section through the device showing the wiringin diagram and the balance mechanism in perspective.

5 'Fig. 2 is a horizontal section taken along the line 22 in Fig. 1. I

Fig. 3 is a perspective view of one of the special powder holding cups.

Fig. 4 is a perspective view of the device withm out the storage hopperor cups.

listening in detail to the drawing, there is shown a cabinet consistingof the side walls iii, the bottom Ii, and top i2. The dividing walls l8extend transversely across the cabinet divid- 5 ing it into threecompartments, which are desigthat a variable factor, such as a currentflow,

ment is mounted an exciter lamp 2i whose base 22 is hinged on a support23 and is adjustable by means of a screw 24 so as to allow the lamp 2ito be moved in an arc.

The light from the lamp 2| is permitted to shine over the dividing wallsl3 through the ports l1 and [8.

The cells i9 and 20 are oppositely connected by means of the wires 25and 26, that is, the positive pole of the cell 20 is connected to thenegative pole of the cell l9, and the positive pole of the cell I9 isconnected to the negative pole of the cell 20.

.Interposed in the circuit between the cells l9 and 20 and in seriestherewith is the resistance element 21, the values of which can'be madeoptional. The cells 19 and 20 are connected to a sensitive galvanometer28, whose needle 29 is adjustable with relation to the scale 80, thatis, when no current is flowing between the cells it! and 28, the needle29 will point to the zero mark II.

The galvanometer 28 is connected to the cell wires 25 and 28 by means ofthe leads 82 and 33, which include a manually operated switch 34. 1

Energy is supplied to the lamp 2| and the galvanometer 28 by means of abattery through the circuit M under the control of a manually operatedswitch 81.

Surrounding the ports I! and I! are the upturned flanges 88 which formsupports for the gage holding cup 89 and work holding cup 48. The gagecup 88 consists of a cylindrical shell 4| provided with a transparentbottom 42 upon which is placed a quantity of material suchi'as magnesiumoxide 43, upon which is placed, a resilient substance 44 which isconflned by means of a cover plate 45.

The work holding cup 40 is also provided with a transparent bottom 48which is of identical thickness and transparency as the bottom 42.

Supported over the port I8 on the standards 41 is a hopper 48 in thebottom of which is placed a sifter, not shown, whichis operated by meansof a crank 49, and its. discharge spout 80 is directly over the cup 40when placed over the port I8. I

Before entering into an explanation of this device, it will beunderstood that the galvanometer 28 is of a conventional type, andincludes a mirror 8| which is mounted on a torsion wire 52, and the lamp58, which is in the circuit 38, projects its beam of light 54 againstthe mirror ii, and the reflected ray constitutes the needle 28, and theadjustment of .the wire 52 is such that the ray-or needle 29 rests atthe zero mark 3| when no current is flowing through the circuit 32-43.

Before this device is used to calibrate a color, a pair of identicalcups 39 with identical filling substances, such asmagnesium oxide 43,are placed over the two ports I! and I8, the switch 34 being open.

Now if the exciter lamp 2| is energized by closing the switch 31 and themeter switch 34 is closed, and the two cups 39 with identical specimensare placed above the ports I! and I8 as stated, and all of theconditions being equal, cell l9 will produce the same amount ofpotential v as does cell 20, and the needle 29 will remain at zero.

specimen, the standard cup "39 which is over the port I8 is removed, anda work holding cup 40 is substituted therefor. The crank 49 is thenrotated to permit a quantity of substance 55,

which for example, is flour, to sift through into the cup 40, and restupon the transparent bottom 46. Any difference in color between thesubstances and the standard substance 43 will affect the output of cell20, causing an unbalance between the two cells 19 and 20-and vary theposition of the needle 29.

The observer then adjusts the resistance 21 to restore the balance,bringing the needle 29 back to zero, and the adjustment or resistancewhich he supplies in ohms is read in terms of color values.

In other words, zero is an absolute and constant point and use is madeoi. the value of. the

decade of resistance in ohms as a calibration value, and departures fromzeroare balanced or measured as accurately as resistance can bemeasured.v

It must be observed that these measurements are taken at moments of zeropotential, making it possible to calibrate the colors with the utmostprecision.

Obviously, any predetermined numbers or values may be ascribed to thevarious portions of the color scale, being thereafter possible to returnor to refer to a given color or shade in a very definite manner.

I am aware that color matching machines have been constructed in thepast, and that photoelectric cells have long been employed for thispurpose; but the dev which I have described herein relates es a" r tocolor calibration and to a means for actually measuring departures froma fixed colorstandardand for ascribing values to these departures.

I claim:

A color calibrator consisting of a casing having a pair of ports in thetop thereof, a pair of glass bottom material holding cups adapted to beremovably placed over said ports, one of said cups containing a materialwhich has standard reflecting properties while the other cup containsmaterial to be compared with the standard, an adjustably mounted exciterlamp within said casing adapted to project light through the bottoms ofboth cups, a photoelectric cell mounted within said casing under each ofsaid cups so as to receive light reflected from the material'theretweensaid cells.

, FRED A. ROGERS.

